On the halo-mass and radial scale dependence of the lensing is low effect

TL;DR

This paper investigates the consistent low lensing amplitude observed in BOSS LOWZ galaxies across various scales and masses, challenging standard $ m f extLambda$CDM predictions and constraining new physics explanations.

Contribution

It provides new measurements and modeling showing a scale- and mass-independent lensing offset, constraining astrophysical and new physics explanations for the effect.

Findings

Lensing amplitude is about 35% lower than $ extLambda$CDM predictions.

The offset is independent of halo mass and radial scale within specified ranges.

Constraints on new physics are tight due to CMB and expansion history measurements.

Abstract

The canonical $\Lambda$CDM cosmological model makes precise predictions for the clustering and lensing properties of galaxies. It has been shown that the lensing amplitude of galaxies in the Baryon Oscillation Spectroscopic Survey (BOSS) is lower than expected given their clustering properties. We present new measurements and modelling of galaxies in the BOSS LOWZ sample. We focus on the radial and stellar mass dependence of the lensing amplitude mis-match. We find an amplitude mis-match of around $35\%$ when assuming $\Lambda$CDM with Planck Cosmological Microwave Background (CMB) constraints. This offset is independent of halo mass and radial scale in the range $M_{\rm halo}\sim 10^{13.3} - 10^{13.9} h^{-1} M_\odot$ and $r=0.1 - 60 \, h^{-1} \mathrm{Mpc}$ ($k \approx 0.05 - 20 \, h \, {\rm Mpc}^{-1}$). The observation that the offset is both mass and scale independent places important constraints on the degree to which astrophysical processes (baryonic effects, assembly bias) can fully explain the effect. This scale independence also suggests that the "lensing is low" effect on small and large radial scales probably have the same physical origin. Resolutions based on new physics require a nearly uniform suppression, relative to $\Lambda$CDM predictions, of the amplitude of matter fluctuations on these scales. The possible causes of this are tightly constrained by measurements of the CMB and of the low-redshift expansion history.